<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    手机号码: <input type="number"> <button>submit</button>
</body>
<script>
    let time = 9;
    let btn = document.querySelector('button');
    btn.addEventListener('click', function(){
        btn.disabled = true;
        let timer = setInterval(function(){
            if(time===0){
                clearInterval(timer);
                btn.disabled = false;
                btn.innerHTML = 'submit';
            } 
            else{
                btn.innerHTML = '还剩下'+time+'秒';
                time--;
            }
        }, 1000);
        time = 9;
    });
</script>
</html>